The task of teaching writing to students in business, engineering, design, computer science, accounting, and other professional areas raises the question of what knowledge the writers call upon to create a rhetorically effective writing plan. Research suggests three plausible answers: their knowledge of schemata, the structure of their topic knowledge, and the constructive process of rhetorical problem solving. The knowledge that has the most visible effect on student performance is rhetorical problem solving. Designing rhetorically sophisticated courses in professional writing, then, requires that English instructors (1) recognize the different kinds of knowledge writers need, (2) teach for the significant tasks, and (3) teach from their special strength--rhetorical problem solving. Writers rise to rhetorical problem solving during at least three occasions: in exploring the rhetorical problem (especially at the outset), in creating a plan, and in reviewing and testing both plans and texts. The methods of exploration professional writers use are adapted to the task at hand or to a given discourse. In addition, they themselves may vary in the methods they use to explore a complex problem. The path from plan to text is a series of rhetorical decisions in which the writer's plan and purpose are instantiated in the choice of a top-level discourse topic which is in its turn elaborated by a series of related sentence topics. Testing the text simply means simulating the reader's comprehension process. To prepare for writing beyond the classroom, students need to work on realistic tasks, learn rhetorical strategies, and develop a meta-awareness of their own strategic processes. (HOD)